Effect of Spinal Sympathetic Blockade upon Local Regulation of Blood Flow in Subcutaneous Tissue

Abstract

The influence of spinal sympathetic blockade upon local regulation of blood flow in subcutaneous adipose tissue was investigated in six subjects. The effect of changes in orthostatic pressure on blood flow in subcutaneous tissue in the crus and distal forearm was measured before and after sympathetic blockade obtained by epidural anesthesia in 4 subjects and by a bilateral sympathectomy in 2 patients suffering from manual hyperhidrosis. Blood flow in subcutaneous tissue measured by 133Xe washout technique decreased by about 40 per cent when the limb was lowered, and remained constant during 30 cm elevation. This was found both before and after the blockade, though in one of the patients, the orthostatic decrease in blood flow was less pronounced 24 h after sympathectomy. Hence central sympathetic reflexes do not alter local orthostatic changes of blood flow in subcutaneous tissue. These changes therefore are most likely due to local mechanisms.

A reassessment of mercury in silastic strain gauge plethysmography for microvascular permeability assessment in man.

“…the veni-arteriolar reflex, as first proposed by Henriksen & Alsner (1957). However, our preliminary observations on patients with proven neuropaphy, those with unilateral sympathectomy and those with epidural anaesthesia have not, as yet, provided any clear answer.…”

Whole-Body Heating Decreases Skin Vascular Response to Low Orthostatic Stress in the Lower Extremities

“…This response to an increase in venous pressure has been demonstrated in human cutaneous tissue [8,28,29]. It has been shown to be due to a local sympathetic reflex mechanism, the venoarteriolar reflex [3,30,31]. Crandall et al [8] have reported that the venoarteriolar response in the skin did not occur through α-adrenergic mechanisms and suggested that it is due to myogenic mechanisms associated with changes in vascular pressure, or it is a nonadrenergic, but neurally mediated, response.…”

Relationship of lower extremity skin blood flow to the ankle brachial index in patients with peripheral arterial disease and normal volunteers

“…doi:10.1016/j.ijcard.2004.08.043 extended position at rest using a sphygmomanometer and can be measured in the skin, on the dorsum of the foot with a laser Doppler (LASERFLO tm Blood Perfusion Monitor Vasamedics Inc Minnesota, USA), or in the popliteal artery with duplex arteriography [2]. In normal subjects, increases in lower extremity venous pressure induce a reduction in microcirculatory blood flow by arteriolar precappillary sphincter vasoconstriction [2,6,17]. Thus, externally applied pressure increases lower extremity venous pressure hence inducing this VAR at a particular cut off pressure.…”

“…It has previously been shown that lower extremity skin microcirculatory flow as measured with modalities like laser Doppler flowmetry decreases with postural changes of the lower extremity (called the veno-arteriolar response or VAR) [2,6]. This is a principal auto regulatory response of the lower extremity arterial vasculature [6][7][8].…”

“…This is a principal auto regulatory response of the lower extremity arterial vasculature [6][7][8]. VAR is a fractional change in skin blood flow from the extended to the flexed positions.…”